CVE-2026-54428 in Apache HttpComponents Core
Allocation of resources without limits or throttling in the HTTP/2 HPACK decoder in Apache HttpComponents Core (5.4.2 and earlier, 5.5-beta1 and earlier) allows an remote attacker to cause a denial of service through memory exhaustion by sending oversized compressed header blocks before the HTTP/2 SETTINGS acknowledgement causes the configured header list size limit to be applied.
Quick answer
Apache Software Foundation Apache HttpComponents Core should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- Apache HttpComponents Core httpcore5-h2 5.4.2 and earlier
- Apache HttpComponents Core httpcore5-h2 5.5-beta1 and earlier
Fixed versions
- Apache HttpComponents Core httpcore5-h2 5.4.3 or later
- Apache HttpComponents Core httpcore5-h2 5.5-beta2 or later for the beta line
How to fix it
CVE-2026-54428 affects Apache HttpComponents Core. In simple terms, the service may slow down, crash, or stop answering. Update to Apache HttpComponents Core httpcore5-h2 5.4.3 or later; Apache HttpComponents Core httpcore5-h2 5.5-beta2 or later for the beta line. If you cannot update today, limit who can reach this system until the fix is done.
- Find every place where Apache HttpComponents Core is installed or used.
- Check if the version matches: Apache HttpComponents Core httpcore5-h2 5.4.2 and earlier; Apache HttpComponents Core httpcore5-h2 5.5-beta1 and earlier.
- Update to: Apache HttpComponents Core httpcore5-h2 5.4.3 or later; Apache HttpComponents Core httpcore5-h2 5.5-beta2 or later for the beta line.
- If you cannot update now, allow only trusted users and trusted networks.
- Check logs for crashes, strange requests, failed logins, or unexpected access.
- Change secrets or passwords if you think data may have been exposed.
Scan now. Google sign-in is only needed to unlock fix guidance.
Verify the fix
- Confirm the installed version is now: Apache HttpComponents Core httpcore5-h2 5.4.3 or later; Apache HttpComponents Core httpcore5-h2 5.5-beta2 or later for the beta line.
- Confirm the risky feature is no longer exposed to untrusted users.
- Run the affected workflow again and make sure it still works.
- Review logs again after the update.
- Run a new Fixnx scan if this software is part of a public website.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-54428?
Apache Software Foundation Apache HttpComponents Core versions listed as affected should be reviewed: Apache HttpComponents Core httpcore5-h2 5.4.2 and earlier, Apache HttpComponents Core httpcore5-h2 5.5-beta1 and earlier.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.